<template>
  <div class="todo-footer" v-show="todos.length>0">
    <label>
      <input type="checkbox" v-model="isAll"/>
    </label>
    <span>
          <span>已完成{{doneTotal}}</span> / 全部 {{todos.length}}
    </span>
    <button class="btn btn-danger" @click="clearAll" style="display: block">清除已完成任务</button>
  </div>
</template>

<script>
export default {
  name: "MyFooter",
  data() {
    return {}
  },
  props: ['todos'],
  watch: {
    index: function () {
      this.index = this.todos.length
    }
  },
  computed: {
    doneTotal() {
      return this.todos.reduce((pre, todo) => pre + (todo.done ? 1 : 0), 0);
    },
    isAll:{
      get(){
        return this.doneTotal === this.todos && this.todos.length > 0
      },
      set(value){
        this.$emit('checkAllTodo',value);
      }
    }
  },
  methods:{
    clearAll(){
      //接收父组件传过来的方法 在子组件使用单击事件去调用
      this.$emit('clearSelect');
    }
  }
}
</script>

<style>
/*footer*/
.todo-footer {
  height: 40px;
  line-height: 40px;
  padding-left: 6px;
  margin-top: 5px;
}

.todo-footer label {
  display: inline-block;
  margin-right: 20px;
  cursor: pointer;
}

.todo-footer label input {
  position: relative;
  top: -1px;
  vertical-align: middle;
  margin-right: 5px;
}

.todo-footer button {
  float: right;
  margin-top: 5px;
}

</style>